Do all multiport valves have an o-ring?

cesmode

Well-known member
Jun 9, 2017
53
Hackettstown
I have a pentair multiport valve that I opened up yesterday. I didnt see an o-ring, I only saw the spider gasket. I might give another look today, but if all MPV should have an o-ring, what could have possibly happened to this one? sucked through backwash or something? The entire pool and filter is only 3 years old, and Ive never any problems with the pool (until this season).